Several field-tests of the PAMM system were made at the Cadbury Commons eldercare facility in Cambridge, MA. PAMM was used by men and women ranging in age from 75 to 95 years old. The system can be seen with an elderly user in Figure 1. The admittance model, ergonomics, and overall user acceptance of PAMM were evaluated.
Figure 1: Field trials of MOD I System.
It was first observed that, while walking, users held PAMM too far in front of them for it to provide good physical support. The users had difficulties keeping the cane close to them possibly because of their fear of tripping over the base. To encourage users to hold it close enough to receive support, an offset handle has been designed and fabricated. Results show that this change permits the user to obtain more support from the device.
The recent field trials also provided information on user acceptance of PAMM. While users had a bit of trouble controlling it at first, many of them adapted to it with practice. The elderly generally require "training" for common mobility aids, like canes and walkers. This is usually provided by physical therapists. The results show that certain admittance models make adaptation to PAMM difficult. The users, for example, found it difficult to guide the cane accurately when it used an admittance model with large damping. The users also had difficulty applying a forward force to move the cane along without also applying a torque to the handle. This resulted in rotational oscillations of the cane. Some of the users also had trouble adjusting to the non-holonomic nature of the device.